Lens-blank manufacture.



E. A. VORNHOLT.

LENS BLANK MANUFACTURE.

APPLICATION FILED AUG-25, I913.

wmm Patented 001:. 19, 1915.

W! TIVESSES:

EDWARD A. volannoL'r, or TOLEDO, OHIO,

KRYPTOK COMPANY, or NEW YORK, n.

Y., A CORPORATION OF NEW YORK.

LENS-BLANK MANUFACTURE.

Specification of Letters Patent:

Application filed August 25, 1913. Serial No. 786,580.

To all whom it may concern:

Be it known that I,.EDWARD A. 'VoRNnoLT,

' a citizen .of the United States, residing at Toledo, Lucas county,Ohio, have invented new and useful Lens-Blank Manufacture, of which thefollowing is a specification.

This invention relates to the manufacture of fused bifocal lenses, theobject being to prevent the-entrapping of air and foreign particlesbetween the welded surfaces of the assembled minor and major blanks ofwhich the bifocal blank is composed.

In carrying out the invention, I aim to insure that the minor blank willbreak down.

progressively from one edge to the other under the action of the heatand thereby insure that all of the air between the abut-' ting surfaceswill be forced out. To accomplish this, I use a clamp or pressure devicewhich bears upon the outer surface and edge of the minor lens blank,which causes said blank to tilt and be held in this tilted position. incontact, at one point only, with themajor blank, the outer or free endof the tilted blank being thus without support. The weight of the blankserves to bend it as soon as softened under the action of the heat, ator near the one point of support, and the blank continues to drop fromthat point diametrically until it finally closes .down and unites withthe major blank, the

gradual bending of the minor lens insuring that all of the air betweenthe surfaces of the blanks will be expelled before they come together.Another advantage afi'orded by thus supporting the minor blank at onepoint in tilted relation with the major blank, is that I a blast orcurrent of air can more readily be directed between the abuttingspaced-apart surfaces immediately before the assembled blanks are placedin the furnace, to remove foreign particles,-such as dust, which mighthave become lodged between the members.

Referring to the drawings: Figure l is a' section through a pair of lenselements clasped on a block showing an embodiment of features of theinvention; Fig. 2 is a plan view of the. elements of Fig. 1; Fig. 3 is aview similar to Fig. 1 showing the way foreign matter may be removedfrom between the clasped lens elements; Fig. 4 is a sectionthrough thelens elements and supporting block, after fusing, in the unionof thelens elements inside the housing-or protecting cover; Fig. 5 is asection through the fin- .turbance of the iently and readily ASSIGNOR,BY MESNE ASSIGNMENTS, TO

Patented Oct. 19, 1915..

different form of seat in a block for clasping lens-elements for fusinginto a bifocal lens blank; and Fig. 10 is a section through a pair oflens elements for a bifocal lens resting upon a supporting block, theclamp for the lens'elements in this instance engaging the lens elementsonly and not clamping the elements to the block.

The primary lens element 1 (Fig. 1) has the seat 2 of concave formground therein to provide a face. The secondary lens element 3 isprovided with an opposing face a. In this instance the secondary lenselement 3 has in addition to the face 4.-. a seat or flattened portion5. The clamp 6, say of spring metal, may have its extensions 7 drawntogether so that in the mary lens blank 1 and the secondary lens blank 3with respective opposing faces 2 and 4 in position, the clamp may claspor engage the outer face of the secondary lens blank 3 and force itsseat 5 blank 1 by the second leg of the clamp 6 entering therecess orseat 8 in the supporting block 9 for the primary lens blank 1.

As thus clamped in position the primary and secondary lens blankelements may be .disposed in the desired position for fusing, the clamppositively holding the elements in contact relation, the tilting beingefi'ected by the blanks themselves as acting upon each other from theclamped contacting portion.

This contacting portion is local, and. as

shown, away from the more used central portion of the opposing seats 2,4, thereby leaving this most used region clear for the action of a dirtremoving means as a suction nozzle 10, Fig. 3. Accordingly, withoutdisproperly seated primary and secondary lens elements after thehandling thereof, any foreign matter may be convenremoved and blanks mayat .once be mounted on the block 11 and covered by the housing 12 toinsure the continupositioning of the priagainst the primary-lens ance ofthe cleaned relation so that when the fusing follows to cause thesecondary lens element 3 to become the fused secondary element 13 inunion with the primary lens element blank 1, no foreign matter whatevermay be entrained therein and there may be an absolute insurance againstdefect in the used region of the union.

. There may in some instances be perceptible the initial contactingrelation but this is so far removed from the generally used portion ofthe blank as to not interfere therewith and the entire area of theprimary blank and of the secondary blank are accordingly acceptable forcommercial uses in an article of such high standard as to be superior tothe run generally found in practice at the present time. This greatsuperiority in high percentage production is a commercial featureenhancing the value of the devices herein disclosed which are simple forgeneral adaptation. The fusing ofelement 13 into.

union with the primary lens element 1 is followed by a grinding of theseparts into the finished lens 14:, 15 of Fig. 5.

Instead of forming the'contacting seat in the secondary lens element,the end may be accomplished in a different manner as shown in Fig. '6,wherein the primary lens element 16 provided with a seat 17 has theopposing secondary lens element 18 with its face 19.

- This element 18 contacts at the cutaway or seat portion 20 in theprimary element 16 and is held in this position by the clamp 21 coactingin theledge 22 of theblock 23. The clamping has been shown as occurringat the outer edges of the primary and seeondary lens elements and inmost instances for convenience'and economy such location is desirable. i

' Inthe-showing in Fig. 7 the clamp 24 in the block 25 reaches over theedge of the primary blank element 26 .to hold in con- ,tacting relationan edge of the secondary blank 27 away from the edge of the primaryblank 26 which effects a tilting relation but not from an edge point ofeach of the blank elements.

In Fig. 8'the block 28 is. shown with an elongated recess 29 for thereception of the lower prong of the clamping member 30 which reachesoverthe near edge of the primary blank element 31 to hold the secondaryblankelement 32 in edge contact therewith and efiect the tiltingrelation from-an edge of each of said blank elements.

device 37 coacts with the primary lens element blank 38 having the planeseat 39 opposing which is the secondary blank element 40 having a.curved opposing seat 41. In this instance as in some others a secondaryseating face is not established to bring about the tilting relation bythe holding clamp and still the holding clamp may be effective for localengagement. Again in thisinstance the clamp clasps only the lenselements to hold them in the desired opposed relation and does not clampthem to the fuse block. In this positive holding by clasping of theprimary and secondary lens elements in position the initial contactpoint is a minimum and after the fusing the ready removal of the holdingmeans leaves no mark whatever upon the blank which is then ready forgrinding. This means that when the primary lens element is to finish fora 25 111. m. disk, a disk of that size may be used initially, a featuremeaning very considerable saving in labor and material,in labor that thesmaller disk maybe prepared more cheaply and in material in that all ofthe material is used with no waste. The clasp or clamp may or may not beof resilient material, the feature being to engage for tilting theelements and for the fusing the clamp may be of a character that it maybe discarded. Again, in this character of secondary lens element, thereis in the combination a regular continued departure from the seating orcontact position and the melting down temperature for fusing may be aminimum in that there is no obstruction or abrupt lines to be overcomein the fusing of this secondary disk. This is an economy in heating orfusion which extends still further in that it keeps the lower meltingpoint effected, for as this heat is not sufficient to distort the seatinthe major lens element of crown glass as the minor lens element of flintglass 18 unltlng therewith, there is not a sufficient softening of thecrown glass to adhere to the support or block, and roughening from thissource is totally avoided and chalking to prevent sticking thus iseliminated and dust therefrom avoided. This added cleanliness precludesaccidental dust defects in the fused articles.

-What is claimed and it is desired to secure by Letters Patent is:

1. The process of making blanks for bifocal lenses consisting in forminga seat in one lens element, holding a second lens cletone lens element,supporting a second lens element at one point only adjacent to said seatand subjecting the elements to heat until the second element breaks downand rests throughout its face in contact With said seat.

3. The process of making blanks for bifocal lenses Which consists informing a seat in one lens element, placing a second lens element oversaid seat, holding the second element in a tilted position by pressureupon one edge thereof and subjecting the assembled elements to heatuntil the second element has settled into the seat in the first element.

4. The process of making blanks for bifocal lenses consisting in forminga curved cavity in one lens element, forming a convex face on avsecondlens element, pressing the two elements together at one point of contactadjacent the edge of said cavity and thereby tilting one element withrespect to the other and subjecting the elements to heat While thus helduntil the second element falls into and fills the cavity in the firstelement.

In testimony whereof I hereunto set my hand in the presence of twowitnesses.

EDlVARD A. VORNHOLT. -Witnesses:

E. C. Momma, GEO. E. KIRK.

